Electrical delay line



0t 22, 1957 E. E. ECKLUND x-:TAL 2,810,887

ELECTRICAL DELAY LINE Filed June 9, 1953 F ig. 2

INVENTORS ELVIN E. ECKLUND BY NORMAN W. GAW,JR.

ATTORNEYS United States Patent O ELECTRICAL DELAY LINE Elvin E. Ecklund, Park Ridge, and Norman W. Gaw, Jr.,

Jersey City, N. J., assignors to Allen B. Du Mont Laboratories, Inc., Clifton, N. J., a corporation of Delaware Application June 9, 1953, Serial No. 360,488

18 Claims. (Cl. S33- 31) This invention relates to delay lines and more specifically to helically or spirally wound delay lines.

To provide desired characteristics in an electrical delay line, certain :relationships between inductance and capacitance are required and must be constant throughout the length of the line. To provide constant incremental capacitance for a long line the spacing between the line and the ground plane must not vary. Also uniform low dielectric constant and low dissipation-factor must exist over a wide frequency range. Where the line is formed in a spiral or helical shape, electrical shielding between the turns must be provided.

Accordingly, one object of this invention is to provide a means for obtaining constant incremental capacitance for a long spiral or helical line by use of a form with a particular shape.

Another object is to provide means for electrically shielding the individual turns of a spiral or helical line.

Still another object is to provide the above economically and without ditiiculty.

Other objects will become apparent from a study of the specication in connection with the attached drawing in which,

Figure l is a side View, partly in section, of a helical delay line constructed in accordance with the invention;

Figure 2 is an enlarged view of the section A of Figure l;

Figure 3 is a sectional view taken along the lines 3-3 of Figure l; and

Figure 4 is an elevational view of a portion of the conductor showing the manner in which the coil is wound.

This invention is particularly useful for xed or continuously variable delay lines such as is described in copending application, Serial No. 320,424, tiled November 14, 1952, by Melvin B. Kline, and assigned to the same assignee as the instant invention.

Referring now to Figure l, which is a partly sectionalized view of a helically wound delay line, reference character 11 denotes a cylinder formed of insulating material, such as phenolic resin or plastic having two grooves formed helically thereof. One groove 12 is shaped to support the inductance element 13 of a delay line and the other groove 16 is shaped to support a conductive element 17 forming, together with the inductive element 13, the capacitive element of the line and serving also as a shield.

The line 13, shown in detail in Figure 4, comprises an inductance wound around a core 14 which may be metallic or non-metallic, magnetic or non-magnetic, depending on the characteristics desired of the delay line. In forming the inductance a coil 15 of a conductor such as enarneled copper wire is wound about the core 14. Coil 15 may be closely wound as shown in Figure 4 or the turns may be spaced. Close winding has the advantage of increased inductance and capacitance per unit length.

The shield 17 may be made up of several strands of wire successively wound into the groove 16 as shown. This wire may be either bare or insulated, may be of "ice the same diameter as the line itself, may consist of many strands of small diameter or may be a metallic foil or sprayed or brushed metallic conducting paint. The relationship of the combined ground shield to the line must be such that fringe coupling between turns of the helically formed line is negligible. Thus the ground-shield extends above and below the line as shown.

While a single embodiment of the invention has been described in detail it will be understood that the inductance and shield member could be spirally wound in a single plane and that many other modifications might be made without departing from the scope of the invention.

We Wish therefore to be limited not by the foregoing description but solely by the claims granted to us.

What is claimed is:

l. A delay line, which comprises a body of electrically insulating material having a pair of helical grooves of the same pitch formed thereon, one of said grooves being relatively shallow and the other relatively deep, said second groove being narrower than said iirst groove, a conductor comprising a plurality of turns of high conductivity material wound upon and insulated from a base material in said first groove, and a shielding and capacitive merribcr comprising a plurality of layers of metallic conductors in said second groove.

2. A delay line, which comprises a body of electrically insulating material having a pair of helical grooves of the same pitch formed thereon, one of said grooves being relatively shallow and the other relatively deep, said second groove being narrower than said first groove, a conductor comprising a plurality of turns of high conductivity material wound upon and insulated from a base material in said iirst groove, and a shielding and capacitive member comprising a layer of metallic foil in said second groove.

3. A delay line, which comprises a body of electrically insulating material having a pair of helical grooves of the same pitch formed thereon, one of said grooves being relatively shallow and the other relatively deep, said second groove being narrower than said first groove, a conductor comprising a plurality of turns of high conductivity material wound upon and insulated from a base material in said irst groove, and a shielding and capacitive member comprising a layer of metallic conducting paint in said second groove.

4. A delay line which comprises a generally cylindrical body of electrically insulating material having a helical rib formed thereon, a helical groove in said body between turns of said rib, a second groove in said rib, a conductor comprising a plurality of turns of high conductivity material wound upon and insulated from a base material in said first groove, and a shielding and capacitive member comprising a plurality of layers of metallic conductors in said second groove.

5. The device of claim 4 in which said shielding and capacitive member lies in said second groove and extends from a cylinder defined by the axis of said conductor in at least one radial direction at least to the cylinder deined by the surface of said conductor.

6. The device of claim 4 in which said shielding and capacitive member lies in said second groove and extends from a cylinder defined by the axis of said conductor in at least one radial direction beyond the cylinder deiined by the surface of said conductor.

7. The device of claim 4 in which said shielding and capacitive member lies in said second groove and extends from a cylinder defined by the axis of said conductor in both radial directions to at least one of the cylinders deiined by the surface of said conductor.

8. The device of claim 4 in which said shielding and capacitive member lies in said second groove and extends from a cylinder defined by the axis of said conductor in both radial directions beyond the cylinders defined by the surface of said conductor.

9. A delay line which comprises a generally cylindrical body of electrically insulating material having a helical rib formed thereon, a helical groove in said body between turns oi said rib, a second groove in said rib, a conductor comprising a plurality of turns of high conductivity material wound upon and insulated from a base material in said first groove, and a shielding and capacitive member comprising a layer of metallic foil in said second groove.

10. The device of claim 9 in which said shielding and capacitive member lies in said second groove and extends from a cylinder defined by the axis of said conductor in at least one radial direction at least to the cylinder defined by the surface of said conductor.

l1. The device of claim 9 in which said shielding and capacitive member lies in said second groove and extends from a cylinder defined by the axis ofY saidconductor in at least one radial direction beyond the cylinder defined by the surface of said conductor.

12. The device of claim 9 in which said shielding and capacitive member lies in said second groove and extends from a cylinder defined by the axis of said conductor in both radial directions to at least one of the cylinders defined by the surface of said conductor.

13. The device of claim 9 in which said shielding and capacitive member lies in said second groove and extends from a cylinder defined by the axis of said conductor in both radial directions beyond the cylinders defined by the surface of said conductor.

14. A delay line which comprises a generally cylindrical body of electrically insulating material having a helical rib formed thereon, a helical groove in said body between turns of said rib, a secondv groovel in said rib, a conductor comprising a plurality of turns of high conductivity material wound upon and insulated from a base material in said first groove, and a shielding and capacitive member comprising a layer of metallic conducting paint in said second groove.

15. The device of claim 14 in which said shielding and capacitive member lies in said second groove and extends from a cylinder defined by the axis of said conductor in at least one radial direction at least to the cylinder defined by the surface of said conductor.

16. The device of claim 14 in which said shielding and capacitive member lies in said second groove and extends from a cylinder defined by the axis of said conductor in at least one radial direction beyond the cylinder defined by the surface of said conductor.

17. The device of claim 14 in which said shielding and capacitive member lies in said second groove and extends from a cylinder defined by the axis of said conductor in both radial directions to at leastV one of the cylinders defined bythe surface of said conductor.

18. The device of claim 14 in which said shielding and capacitive member lies in said second groove and extends from a cylinder defined by the axis of said conductor in both radial directions beyond the cylinders defined by the surface of said conductor.

References Cited in the file of this patent UNITED STATES PATENTS 1,608,673 Schroder Nov. 30, 1926 1,852,605 Carlton et al Apr. 5, 1932 2,178,653 Slade Nov. 7, 1939 2,452,572 Iago Nov. 2, 1948 2,457,212 Di Toro Dec. 28, 1948 2,462,410 Lindenblad Feb. 22, 1949 2,467,857 Rubel et al Apr. 19, 1949 2,507,358 Waggoner May 9, 1950 2,619,537 Kihn NOV. 25, 1952 

